The proposed project aims at developing a novel quadrupedal human-assistive robotic platform (Q-HARP}, with the objective of helping the large number of elderly individuals live a healthy, physically active life style. The Q-HARP primarily functions as a smart power-assist walker: a user, situated in the center of the legged robot, can enjoy the desired amount of power assist in walking according to his/her intent. As such, a Q-HARP user is able to perform an appropriate amount of physical activity, while enjoying the enhanced level of mobility during his/her daily lif. Furthermore, with the Q-HARP's legged motion, the human-robot system can easily overcome most obstacles in the daily life. With this capability, the Q-HARP has a potential of becoming a basic building block for Aging-in-Place, enabling elderly individuals to stay in their home longer without conducting costly modification to their existing home structures. To develop this innovative robot, the investigators will conduct research in various aspects of the project. The specific aims of the project are: AIM 1) Understand user needs and promote user involvement in the research process; AIM 2) Create a systematic design framework for the human-assistive quadrupedal robot, and build robot prototypes for experimental testing; AIM 3) Develop a 3D computer vision-based approach for motion and environment detection; AIM 4) Study the human assistive strategies in assistive walking and emergency response; AIM 5) Develop an intelligent robot control system for interactive assistance in locomotion; AIM 6) Conduct experiments to test the robot performance in human assistance tasks. The project's potential bene*fits to society are substantial. By 2030, there will be 71 million older adults living in the S, accounting for 20/o of the entire population. For the health and well ness of older adults, a key contributing factor is to be physically active. However, a large number of older adults have significant difficulty in staying physically active due to mobility impairment. By providing desire physical assistance in the coordinated locomotion, the Q-HARP is anticipated to restore an elderly person's mobility, keep him/her physically active, and enjoy a more healthy life with reduced reliance on the assistance of caregivers.